*{
    padding: 0;
    margin: 0;
}
body{
    width: 100%;
    height: 200vh;
}

#left,#right{
    width: 200px;
    height: 200px;
    background: pink;
}
#left {
    position: absolute;
    left: 0;
    top: 0;
}
#right{
    position: absolute;
    right: 0;
    top: 0;
}
#middle{
    margin: 0 200px;
    height: 200px;
    background: lightblue;
    overflow-y: scroll;

}